Post-treatment with 9cRA attenuated the loss of TH cells in nigra. TH immunoreactivity was conducted at >2 months after unilateral 6-OHDA lesioning. (A) Almost no TH activity was found in the lesioned side nigra (left panel, rostral nigra; middle and right panels, caudal nigra) in 3 vehicle treated animals. Treatment with 9cRA partially blocked the loss of TH immunoreactivity in another 3 lesioned rats. (B) Labels in each panel correspond to the blocks at higher magnification in (A). Note that almost no TH cells in lesioned SN in the vehicle treated rat (B-a). In contrast, TH (+) cells were found in rostral (B-b) and caudal (B-c,d) SN in the lesioned rats treated with 9cRA.